The thermal efficiency of a spark ignition internal combustion engine is usually between 20 and 25 percent, and the compression ignition internal combustion engine (diesel) is usually between 29 to 35 percent. The difference in thermal efficiency is caused by the difference in compression ratios between the two engines. The higher the compression ratio the greater the thermal efficiency, because during the power stroke (of the four stroke cycle) the compressed gases can do more work on the piston when it has a higher expansion ratio. Therefore an internal combustion engine can attain a thermal efficiency of up to 35 percent by increasing the compression ratio.
The thermal energy which is not converted into work (65 percent on a modern diesel engine) is lost to the environment 45 to 55 percent as heat losses and 10 to 20 percent by mechanical and frictional energy losses.
To increase the efficiency of an internal combustion engine with a high compression ratio, it is necessary to reduce the thermal energy losses. The present invention pertains to the object of increasing thermal efficiency by reducing thermal energy losses.